PHP is the longest language I have worked on out of the bunch. I started out using it for building websites back in the day. These days, I mostly employ the language for building backend APIs for database applications. Below are just the basics on PHP, for reference purposes only.
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BOF and EOF
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<?php /* start and end the code with these tags... */ ?>
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Documentation
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/**
* Function Name
* A description of the what the function is doing
* @param nameOfParameter1 data type
* ...
* @return data type
*/
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Single line comments
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// or #
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Multi line comments
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/* ... */
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EOL delimiter
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;
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Basic Output
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echo "BlinkWiki";
echo("BlinkWiki");
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DATATYPES
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Integer
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// numerical value from -2billion to +2billion, with no decimals
int $count;
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Float
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// numerical value with decimal places
float $count = 20.51;
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String
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// Collection of characters enclosed in quotes
string $message;
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Boolean
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// logical variable that has TRUE or FALSE as value
bool $isReady = true;
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Array
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// collection of items that can be referenced by indices
$words = array("Hello", "BlinkWiki");
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Object
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// instance of a class
$blinkWiki = new BlinkWiki();
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INITIALIZATION
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Naming variables
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$variableName
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Naming constants
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CONSTANT_NAME
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Initializing a constant
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define("PI", 3.14);
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Initializing an integer
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$count = 36;
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Initializing a string
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$message = "Hello BlinkWiki";
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String delimiters
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// Single quotes
$message = 'Hello BlinkWiki';
// Double quotes
$message = "Hello BlinkWiki";
// Multiline
$message = <<<Hello and welcome to BlinkWiki:
This article is on cheat sheets and language comparisons.
>>>;
// Execute the string as shell command
$message = `Hello and welcome to BlinkWiki:
This article is on cheat sheets and language comparisons.`;
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Initializing an integer
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$count = 23;
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Initializing an array
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$messages = [
"Hello",
"Welcome to BlinkWiki",
"Here is a cheatsheet"
];
$scores = array(54, 5, 6, 60, 9, 40, 54);
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OPERATORS
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Operators
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+ // Addition
- // Subtraction
* // Multiplication
/ // Division
% // Modulus division
** // Raised to power
= Equation
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Logical Operators
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|| // Logical OR
&& // Logical AND
== // Logical Equation
=== // Is identical
!= // Logical Inequality
<> // Logical Inequality
!=== // Is not identical
< // Less than
> // Greater than
<= // Less than or equal to
>= // Greater than or equal to
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Assignment Operators
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+= // Add and assign
-= // Subtract and assign
*= // Multiply and assign
/= // Divide and assign
%= // Complete Modulus division and assign
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Increments and Decrements
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++$count // Increase count and then return it
--$count // Decrease count and then return it
$count++ // Return count and then increase it
$count-- // Return count and then decrease it
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String Operators
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Concatenation
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$message = "Blink" . "Wiki"; // returns `BlinkWiki`
$message .= " Cheat Sheets"; // returns 'BlinkWiki Code Sheets'
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CONDITIONALS
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If ... ElseIf ... Else
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if (condition1) {
// run this if condition1 was met
} else if (condition2) {
// run this if condition2 was met
} else {
// run this if neither condition1 nor consition2 were met
}
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Switch ... Case
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switch ($variable) {
case "One":
// $variable == "One"
break;
case "Two":
// $variable == "Two"
break;
case "Three":
// $variable == "Three"
break;
default:
// $variable is not "One", "Two" or "Three"
}
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LOOP CONSTRUCTS
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While
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$i = 0;
// while this condition is still being met
while ($i < 3) {
// TODO: provide the logic
$i++;
echo $i;
}
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Do While
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$i = 0;
// start the loop
do {
// TODO: provide the logic
$i++;
echo $i;
// stop the loop when the condition below has been met
} while ($i < 3);
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Foreach
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// define a collection
$collection = array(0,1,2,3);
// start a loop to go through every item in a collection
foreach ($collection as $number) {
echo $number;
}
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For
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// start the loop from $i = 0 and stop when $i<3
for ($i=0; $i<3, $i++) {
echo $i;
}
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CONSTRUCTS
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Function
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function greet() {
// TODO function logic goes here ...
}
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Function returning a variable
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function greet($parameter) {
// TODO function logic goes here ...
return "Hello BlinkWiki";
}
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Function with Parameter
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function greet($parameter) {
// TODO function logic goes here ...
}
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Function with Parameter
and default value
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function greet($parameter="BlinkWiki") {
// TODO function logic goes here ...
return "Hello " . $parameter;
}
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Function with unknown
number of parameters
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function greet(...$parameters) {
// TODO return the second parameter provided ...
return $parameter[2];
}
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HANDLING ERRORS
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Try ... Throw ... Catch
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try {
// TODO: code that throws an exception on condition
if (exception_condition == true) {
// throw an exception
throw new Exception("There was a problem running this...");
}
// catch the exception
} catch (Exception $e) {
// TODO: inform user of the exception
}
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